GAUHATI, India -- Authorities are searching for poachers who have killed six rare one-horned rhinoceros in the past four months in a protected game reserve in India's northeastern Assam state, the state's chief warden said Tuesday.

Two of the animals were killed in the past week inside the famed Kaziranga National Park, a 166-square mile habitat, said M.C. Malakar, Assam state's chief wildlife warden.

A spurt in poaching has surprised authorities because only five rhinos were killed in 2006 and seven in 2005.

"It is clear funds are flowing to attract shooters to kill rhinos for their horns and we can't rule out poaching syndicates within India and from abroad backing this fresh campaign at targeting rhinos in Kaziranga," Malakar told The Associated Press.

Rhino horns are in great demand globally, particularly in Southeast Asia, for their alleged efficacy in producing aphrodisiacs and traditional medicines. Some people also use them to make decorative dagger handles.

Kaziranga, nearly 135 miles east of Gauhati, the capital of Assam state, has an estimated 1,855 one-horned rhinos out of the estimated global population of some 3,000, according to the last census taken in March 2006.

Conservation efforts have led to a rise in the rhino population and they are now found even on the periphery of the park, making them easier targets for poachers, Malakar said.

The Assam Wildlife Crime Prevention Unit has suggested improvements in the infrastructure of the park and acquiring new speed boats for guards to quickly navigate the streams that crisscross the reserve.

Conservationists, however, say wildlife authorities have annoyed people living in the park's vicinity by not compensating them for loss of their crops ravaged by wild elephants and other animals.

"Poachers are often locals. To get intelligence about poachers' plans, it is very important to have a friendly set of villagers around the park," said Soumyadeep Dutta, who heads Natures Beckon, a conservation group.

According to government figures, 650 one-horned rhinos have been killed in Kaziranga in the past 40 years.